Thanks to a comment from Confirmthem's Andrew Hyman's comment on Poliblog , I saw this explanation on Senator Frist's website explaining why the GOP doesn't opt for a full-out filibuster. It penalizes the majority more than the minority. They would have to keep at least 50 GOP Senators on the floor to answer a quorum call. The Democrats would only need one Senator at a time and that person could just keep making quorum calls.
I'm glad to see that cleared up. But, boy does the Senate have some kooky rules. Only politicians could think these things up.